Hydroxy-polymer solutions in high boiling alcohol solvent cross-linkable with epoxide



United States Patent ()filice 3,247,286 Patented Apr. 19, 1966 ,24 ,2 HYDROXY-POLYMER SOLUTIONS IN HIGH BOIL- ING ALCOHOL SOLVENT CROSS-LINKABLE WITH EPOXIDE John E. Masters and Darrell D. Hicks, Louisville, Ky., assignors, by mesne assignments, to Celanese Coatings Company, a corporation of Delaware No Drawing. Filed Mar. 2, 1960, Ser. No. 12,280 11 Claims. (Cl. 266-837) This invention pertains to the preparation of hydroxypolymers. It is particularly related to processes, for the formation of solutions of hydroxy-polymers which are readily'cross-linked and to methods for preparing molded articles or castings from such polymer solutions.

Hydroxy-polymers are wellknown homopolymers and copolymers containing hydroxy groups. They are generally prepared by the polymerization of unsaturated alcohols or hydroxy esters by solution or emulsion polymerization technique.

In emulsion polymerization the drying of the coagulum is difiicult because of the great tendency of the polymer to coalesce. Subsequent mastication with cross-linking agents is diflicult. Accordingly, emulsion polymerized hydroxy copolymers are generally used as film forming materials rather than in pottings, castings and the like.

Solution polymerization of monomers containing hydroxyl groups and other unsaturated comonomers to form hydroxy copolymers does not lend itself to the formation of molded articles because of the difficulty of removing the solvent. acetone is used it is difiicult to form castings free of entrained solvent or of bubbles resulting from solventliberation. The presence of volatile solvent thus has prohibited an extensive use of hydroxy-substituted copolymers in the potting and castings fields.

By the practice of this invention a process is provided for the preparation of solutions of hydroxy polymers for applications heretofore not practical through the use of polymer solutions. In accordance with this invention the monomers are polymerized in the presence of a reactive solvent. By reactive solvent is meant a non-volatile solvent in which the polymer is soluble at polymerization temperatures and which reacts with the polymer and/or a cross-linking agent for the polymer under curing conditions, that is at curing temperatures and, if necessary, in the presence of a catalyst. It is understood, however, that under polymerizing conditions the solvent and the monomers are substantially non-reactive with each other. In other words, the polymerization medium is a solvent which does not react with the monomer or the polymer during polymerization, but which reacts either with the polymer or the cross-linking agent or both when the temperature is raised above the polymerization temperature generally in the presence of a catalyst.

Polymer solutions are thus formed which can be mixed with cross-linking agents to form cured materials without the need for solvent liberation. This not only renders the polymer solution particularly suitable for pottings, castings, encapsulations, and the like, but also provides a convenient reaction medium for making high polymers which otherwise would be of little value in the formation of shaped articles because of their extreme viscosities.

Reactive solvents which are employed in accordance with the practice of this invention are alcohols boiling at 150 C. or above, and which are liquid at the polymerization temperature employed, that is they have melting points below the polymerization temperature used, gen erally 60 C. to 150 C. The viscosity of the solvents should not be greater than 130 centipoises at the polymerization temperature. Of alcohols serving as reactive solvents herein, monohyd-ric alcohols are suitable, but

Even when a low boiling solvent such as polyhydric alcohols are preferred. However, so long as they meet the boiling point, melting point and viscosity requirements there is no reason why any of these can not be employed.

Monohydric alcohols which are used in accordance with the invention are those which can not readily be liberated by heating the polymer after it is made, such as stearyl alcohol, lauryl alcohol and the like. Generally saturated aliphatic alcohols having from ten to eighteen carbon atoms, such as decyl alcohol, myristyl alcohol, octadecyl alcohol, etc. will be most used, While saturated acids and alcohols are usually employed, it is noted that whether unsaturated alcohols and acids are usable depends on the reactivity of the double bond under polymerization conditions. Thus fatty acids of the drying oil type such as soya, linseed, and oleic acids can be used. Likewise linolyl, farnesol, oleyl and similar higher fatty alcohols which are not readily polymerizable can be used.

Of the alcohols, saturated polyhydric alcohols having one to four hydroxyl groups are preferred. Particularly suitable are the high molecular Weight polyglycols. However, the glycols, glycerin, trimethylol propane. and the like can be used, Suitable glycols are, for instance, etha ylene glycol, propylene glycol, diethylene glycol, 1,5- pentanediol, tripropylene glycol, dipropylene glycol, tetraethylene glycol, triethylene glycol, etc. It is understood that glycols as used herein include both the dihydric alcohols and the dihydric ether alcohols. Thus the commercially available Carbowaxes are contemplated. These are mixtures of polyoxyethylene glycols. Those mixtures having average molecular weights of from 200 to 1000 are particularly desirable. The polyoxypropylene glycols are also contemplated.

It is noted that the reactive solvent need not be a liquid at room temperature. It is necessary only that it have a viscosity of not more than centipoises at the polymerization temperature. It is a low melting compound which will be liquid at the polymerization temperature. The reactive solvents set forth hereinbefore make excellent reaction media. In some cases upon cooling, crystalline solids result which can be readily liquified on heating. If desired the solid polymer-solvent compositions can be pulverized for convenience in use.

Methods of polymerizing the hydroxy monomer, the unsaturated alcohol or ester, with various comonomers are Well known. Polymerization is efiected by convendesired, at a pressure slightly above atmospheric. Thev polymerization reaction is, of course, accelerated by the use of heat and other conditions such as a peroxide or hydroperoxide catalyst, e.g. benzoyl peroxide, cumene hydroperxoide, tertiarybutyl hydroperoxide, phthalic peroxide, acetyl peroxide, lauroyl peroxide, ditertiarybutyl peroxide and the like.

The hydroxy monomer is generally first prepared and then polymerized with the other unsaturated monomer. However, when a hydroxy ester prepared from a monoepoxide and an unsaturated acid is to be used, such as hydroxy propyl acrylate, it can be prepared during the polymerization, if the solvent is not an epoxide. Thus the unsaturated acid, the monoepoxide, the other monomer, and a solvent such as a glycol are all combined and reacted preferably using a polymerization catalyst and a carboxy-epoxy catalyst as shown in some of the eX- amples.

The hydroxy substituted copolymers prepared according to this invention are formed by the reaction of a' monoethylenically unsaturated monomer with an unsaturated alcohol, a hydroxy alkyl vinyl sulfide or a hydroxy ester, each containing only one double bond and one or more hydroxyl groups, and free of other reactive groups. Examples of hydroxy monomers are such esters as hydroxy ethyl acrylate, hydroxy propyl acrylate, hydroxy propyl and ethyl methacrylate, hydroxy ethyl crotonate, hydroxy propyl crotonate, acrylic and methacrylic esters of monohydric alcohol glycidyl ethers, di (hydroxyalkyl) or alkyl, hydroxyalkyl maleate and fumarate esters, and 'monohydric alcohol glycidyl ethers; such unsaturated alcohols as allyl alcohol, crotoyl alcohol, alpha-methyl allyl alcohol, methallyl alcohol, chloroallyl alcohol and beta-methyl crotyl alcohol; and hydroxy ethyl, hydroxy propyl, hydroxy butyl vinyl sulfides, and hydroxy octyl vinyl sulfides; and other hydroxy alkyl esters and hydroxy alkyl vinyl sulfides, having not more than ten alkyl carbon atoms.

Polymerized with the hydroxy monomer is a monoethylenically unsaturated monomer. By a monoethylenically unsaturated monomer is intended an organic compound containing a single vinyl, vinylidene, or vinylene group, desirably a single vinyl group. Preferred monomers are liquids containing a single vinyl group attached to a negative radical and are compatible with the hydroxy monomer or soluble in the reactive diluent. Since such monomers are well known, the following are given here by Way of example:

Monoolefim'c hydrocarbons, that is monomers containing only atoms of hydrogen and carbon, such as styrene, alpha-methyl styrene, alpha-ethyl styrene, alpha-butyl styrene and vinyl toluene, and the like;

Halogenated monoolefim'c hydrocarbons, that is, monomers containing carbons, hydrogen and one or more halogen atoms such as alpha-chlorostyrene, alpha-bromostyrene, -2,5-dichlorostyrene, 2,5-dibromostyrene, 3,4- dichlorostyrene, 3,4-difluorostyrene, ortho-, meta-, and para-fiuorostyrenes, 2,6-dichlorostyrene, 2,6-difluorostyrene, 3-fluoro-4-chlorostyrene, 3-chloro-4-fluorostyrene, 2,4,5-trichlorostyrene, dichloromonofluorostyrenes, chloroethylene (vinyl chloride), 1,1-dichloroethylene (vinylidene chloride), bromoethylene, fluoroethylene, iodoethylene, 1,1-dibromoethylene, 1,1-difluoroethylene, 1,1- diiodoethylene, and the like;

Esters of organic and inorganic acids such as vinyl acetate, vinyl propionate; vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl caproate, vinyl enanthate, vinyl benzoate, vinyl toluate, vinyl p-chlorobenzoate, vinyl o-chlorobenzoate, and similar vinyl halobenzoates, vinyl p-methoxybenzoate, vinyl o-methoxybenzoate, vinyl p-ethoxybenzoate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, decyl methacrylate, methyl crotonate, ethyl crotonate and ethyl tiglate, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, heptyl acrylate, octyl acrylate, 3,5,5-trimethylhexyl acrylate, decyl acrylate and dodecyl acrylate, isopropenyl acetate, isopropenyl 'propionate, isopropenyl butyrate, isopropenyl isobutyrate, isopropenyl valerate, isopropenyl caproate, isopropenyl enanthate, isopropenyl benzoate, isopropenyl p-chlorobenzoate, isopropenyl bromobenzoate, isopropenyl rn-chlorobenzoate, isopropenyl toluate, isopropenyl alpha-chloroacetate and isopropenyl alpha-bromopropionate;

Vinyl alpha-chloroacetate, vinyl alpha-bromoacetate,

vinyl alpha-chloropropionate, vinyl alpha-bromopropionate,.vinyl alpha-iodopropionate, vinyl alpha-chlorobutyrate, vinyl alpha-chlorovalerate and vinyl alphabromovalerate;

Allyl chlorocarbonate, allyl formate, allyl acetate, allyl propionate, allyl butyrate, allyl valerate, allyl caproate, di allyl phthalate, diallyl succinate, diethylene glycol bis(allyl-carbonate), allyl 3,5,5-trimethylhexoate, allyl benzo ate, allyl acrylate, allyl crotonate, allyl oleate, allyl chloroacetate, allyl trichloroacetate, allyl chloropropionate, allyl chlorovalera-te, allyl lactate, allyl pyruvate, allyl aminoacetate, allyl acetoacetate, allyl thioacetate, diallyl-3,4,5, 6,7,7-hexachloro-4-endomethylene tetrahydrophthalate, as well as methallyl esters corresponding to the above allyl esters, as well as esters from such alkenyl alcohols as betaethyl allyl alcohol, beta-propyl allyl alcohol, l-buten-4- o1, 2-methyl-buten-l-ol-4, 2(2,2-dimethyl-propyl)-1 buten- 4-01 and l-pentene-4-ol;

Methyl alpha-chloroacrylate, methyl alpha-bromoacrylate, methyl alpha-fluoroacrylate, methyl alpha-iodoacrylate, ethyl alpha-chloroacrylate, propyl alpha-chloroacrylate, isopropyl alpha bromoacrylate amyl alphachloroacrylate, octyl alpha chloroacrylate, 3,5,5 trimethylhexy-l alpha chloroacrylate, decyl alpha chloroacrylate, methyl alpha cyano acrylate, ethyl alpha cyano acrylate, amyl alpha cyano acrylate and decyl alphacyano acrylate;

Dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, dibutyl ifumarate and diethyl glutaconate;

Organic nitriles such as acryloni-trile, methacrylonitrile, ethacrylonitrile, crotonitrile, and the like;

Acid monomers such as acrylic acid, methacrylic acid, crotonic acid, 3-butenoic acid, angelic acid, tiglic acid and the like can be used if the reactive solvent is not an epoxide;

Amides such as acrylamide, alpha-methyl acrylamide, Nephenyl acrylamide, N-methyl, N p'henyl acrylamaide, and the like.

In forming the cross-linked compositions of this inventi-on, it is particularly desirable to form an epoxy-hydroxyw are generally employed in ratios resulting in a cross-linked thermoset composition, usually from one to two equivalents anhydride to two equivalents polyepoxide to 0.2 to 0.8 hydroxyl equivalent copolymer. By an epoxide equivalent is meant the amount, in grams, of epoxide compound containing one epoxy group. Likewise a hydroxyl equivalent represents the amount (in grams) furnishing the hydroxyl group. An equivalent anhydride is the amount of anhydride which contains one anhydride group. Such anhydride car boxy epoxy systems are particularly preferred when the hydroxy copolymer is made in the presence of a monofunctional reactive solvent. If the reactive solvent is-a monohydric alcohol it will be necessary in order to obtain a cross-linked composition to include some polyfunctional epoxide if an anhydride carboxy hydroxy epoxide system is desired. Of course if the hydroxy \copolymer is made in a monohydric alcohol the copolymer solution can be cured by other means as through hydroxyl groups without using a carboxy hydroxy epoxy anhydride system. How- .ever, since in some instances only part or none of the,

It is understood that in this system such as the hydroxy epoxy anhydride system a catalyst can be employed if desired. Generally speakling known catalyst which are activators for carboxy-epoxy reaction can be used to increase the rate of cross-linking When this system is used, for example, inorganic andorganic bases tertiary amines, quaternary ammonium hydroxides and. alkali metal or alkaline earth metal hydroxides.

Examples are sodium hydroxide, calcium hydroxide, di-

methyl aminomethyl phenol, benzyl dimethyl amine and thelike. Particularly desirable catalystsare quaternary ammonium salts such as benzyl trimethylammonium chloride, benzyl trirnethylammonium bromide, benzyl tri- 5 In a one liter, three-necked, round-bottomed flask equipped with thermometer, agitator, and reflux condenser the above listed materials are combined and heated methylammonium acetate, tolyl trimethylamrnonium to reflux temperature (80 C. to '85 C.). The flask conchloride, phenyl trimethyl-ammonium phosphate, benzyl 5 contents is continued until a reflux temperature of 125 trirnethylammonium oxalate, and trimethylhenzyl am- 105 C. at which time a 6.0 grams excess propylene oxide monium lactate. These activators are employed in cataisadded to lower the acid value. Refluxofthe flasklytic quantities, say from 0.05 to 5 percent based on the contents is continued .until a reflux temperature of 125 total composition. Curing conditions will, of course, vary C. to 130 C. is reached. The resulting 50 percent soluwith the particular application. In general the carboxytion of the 50/50 vinyl toluene/hydroxy propyl methepoxy composition with or without the anhydride is heated acrylate copolymer is cooled and poured into a suitable at 150C. to 200 C. and generally at 180 C. to form Container. The copolymer portion of the composition a cross-linked infusible resin. If a catalyst is preferred has an actual acid value of 2 to 4 and a theoretical hythe temperature may be lowered to a low a 125 (1,, dr-oxyl equivalent of 288, while the hydroxyl copolymerthe temperature a d time depending upon the i f th glycol solution has a theoretical hydroxyl equivalent of casting, varying from 125 C. to 200C. and one to four 219. hours with a catalyst and three to twelve hours when no B. Cured composition a ly i is f In a suitable container 75.9 grams (.3'85 hydroxyl mventlon a best further dascnbed by refer equivalent) of the hydroxy copolymer glycol solution ence,tothe following-examples. The exan 1p1es are fo and 71.5 grams (.376 epoxide equivalent) of Epoxide the P F w 1t Intended h 190 are combined with 55.8 grams (.377 anhydride equivno undue limitatlon .be read nto the invention by referr ng alent) of phthauc anhydride vandv are heated at C to exampleszor the dlscusslon P The ,epoxldfi with stirringuntil all of the phthalic anhydride is in solu- IGSIH' employed in the examples (Epoxlde 190) I a 1 tion. Into the mixture is blended .25 gram of dimethylepoxilde W1 th an epoxlde P' of,l9o.prepa red by aminomethyl phenol whereupon the mixture is poured into reacting. eplchlor hYdnm emP1ymg 10 a mold preparedfrom glass plates, and is heated in a mols eplchlomhydrm and one {1101 h i' circulating oven for one hour at 100 C. followed by a The mold used in the preparation of castlngs is made post curing of two hours at C. The casting by wrappmgtwo 8" by 12" by A" glass plat s Wlth heavy tained has these physical properties: duty cellophane so that one side of each plate is free of wrinkles. These plates are then assembled, smooth Tensile :strength q- Side inward, into a mold by separating the plates with Elongatlon 28 P /s" aluminum spacers to adjust the cavity thickness using Impact strength of notchpolyvinyl chloride-acetate plastic tubing as a gasket on Hardness (Rofkwen) 8013 three of the four edges of the glass plates. The two glass 35 Water abso'rlmon P plates are then clamped together using 6 C clamps. F ou-r additional compositions of /50 vinyl toluene/ hydroxy propyl acrylate copolymers each having a hy- EXAMPLE 1 droxyl equivalent of 260 are prepared as describedin the A. Copolymer preparation preceding example. Two of these are 50 percent copol- 40 ymer solutions prepared in a polyethylene glycol mixture Material Units Weight having an average molecular weight of 300 and two are ams) prepared in polyethylene glycol having an average molecular weight of 600. The copolymer compositions are py p l then cast between the glass plates accordance with the @318 815 49 preceding example using a cure schedule of one hour at Benzylfrimethylammonium hl ride (60 percent C. and an additional two hours at C. and the B2I32Zyi33?;:::::::::::::::i::::::::"'I: $18 213 equivalent ratios of anhyd-ride and eroxide shown in Polyethylene glycol (molecular e 300-0 Table IA. The properties of the resulting cured castings are given in Table IB.

TABLE IA Copolymer Copolymer Equivalent Ratios N 0. Copolyrner Concentra- Hydroxyl Reactive copolymer Diluent tion, Percent Equivalent Diluent Appearance v. Copolymer Diluent Anhydride Epoxide 1A 50/50VT/HPA 50 260 PEG300 Flows Clear 1.0 1.73 6.09 5.09 1B 50/50VT/HPA 50 260 PEG300 (l 1.0 1.76 3.80 3.80 1C 50/50VT/HPA 50 260 PEG-600...- 1.0 .875 3.73 3.71 1D 50/50 VT/HPA 50 260 PEG600- l 1.0 .865 2.86 2.70

TABLE IB Tensile Flexure No. Percent Impact 2 Hardness 3 Percent Water Elongation (Notched) bsorb. U1t. Mod. X106 Ult. Mod. X10" 12,300 .25 6.3 19. 400 .50 .63 96 M .1 11,800 .25 5. 2 18, 300 .49 .57 92 M .2 7,100 .28 2. 6 17,600 .50 .52 59 M .2 10, 000 .24 5. 8 14, 900 .43 .82 88 M 4 VT-Vinyl toluene. HPAHydroxy propyl acrylate; PE G- Polyethylene glycol.

1 Lb. per 111.

2 Ft. lbs. per in. notch.

l Rockwell M.

7 EXAMPLE 2 A. Copolymer preparation 1 5 grams in excess of equivalent amount.

As described in the preceding example, the vinyl toluene, acrylicacid, propylene oxide, benzoyl peroxide, benzy-l trimethyl ammonium chloride, and polyethylene glycol are heated together in a flask to reflux temperature (90 C. to 95 C.). The contents of the flask are then 00 ONWO held at a maximum reflux until the temperature reaches 130 C. The acid value of the solids is determined at this point and if it is found to be above 5, an additional 10 grams of propylene oxide are added andthe temperature is held at 130 C. until the acid value is below 2. The flask is then fitted for vacuum distillation and any excess monomer is distilled off at 15 mm. Hg and 127 C. The resulting product is a 50 percent solution of a 70/30 vinyl toluene/hydroxy propyl acrylate copolymer in polyethylene glycol. The copolymer portion "of the composition has a theoretical hydroxyl equivalent of 435 while the total copolymer solution has a hydroxyl equivalent of 293.

B. Cured composition In accordance with part B of Example 1, 79.2 grams of the hydroxy copolymer glycol solution (.301 hydroxyl equivalent of copolymer and .264 hydroxyl equivalent of polyethylene glycol) are combined with 68 grams (.348 epoxide equivalent) of Epoxide 190 and 52.8 grams (.356 anhydride equivalent) of phthalic anhydride. The mixture is heated with stirring at 110 C. until melted. To

the solution is added with stirring, grams of dimethyl amino-methyl phenol. The resulting blend is cast and heated at 150 C. for thirty minutes followed by, a two hour post cure at 180 C. as described in part B of Example 1, producing aha-rd, tough, flexible casting.

1 4.0 grams in excess of equivalent amount.

In accordance with the preceding examples, the vinyl The copolymer solution is cast and cured as described in part B of Example 2, producing a thermosetting resin having very good toughness, flexibility, and resistance to impact. 0

EXAMPLE 4 A. Copolymer preparation Weight Material: (grams) Propylene oxide 1 43.6 Acrylic acid 54.0 Vinyl toluene 97.6 Benzoyl peroxide 4.0

Benzyltrimethylammonium chloride percent aqueous solution) 4.1 Polyethylene glycol (molecular weight, 600)-.. 200.0

1 Plus 24.8 grams excess of equivalent amount.

In a one liter, three-necked, round-bottomed flask equipped with thermometer, agitator, and reflux condenser the above listed materials are combined and heated to reflux temperature C. to C.). The flask contents are held at reflux for about six and one-half hours at which time the reflux temperature is 98 C. The course of the .reaction is followed by determination of the acid value based on solids. 'At the end of six and one-half hours reflux the determined acid value in this case is 2.0. The flask is then fitted for vacuum distillation, and the excess propylene oxide is distilled off at 15 mm. Hg to a tempera ture of 98 C. After all excess propylene oxide is removed, .the 5 Opercent solution of the 50/50 vinyl toluene/ hydroxy propyl acrylate copolymer is cooled to room temperature and poured in a suitable container for storage. The copolymer portion has a theoretical hydroxyl equivalent of 260, while the total copolymer solution has a theoretical hydroxyl equivalent of 520.

B. Cured composition In a suitable container, 29.3 grams (0.105 hydroxyl equivalent) of the hydroxy copolymer glycol solution, and

- Tensile strength 7100 lb./sq. in.

Elongation 2.6 percent. Flexural strength 17,600 lb./sq. in. Impact strength 0.52 ft. lb./in. of notch. Hardness (Rockwell M) 89. Water absorption 0.2 percent.

toluene, propylene oxide, methacrylic acid, catalysts, and

propylene glycol are heated together in a one liter flask to reflux (83 C.). Reflux is maintained until the temperature of the flask contents reaches C., a period of about three and one-half hours. The resulting product is a 50 percent solution of a 50/50 vinyl toluene/hydroxy propyl methacrylate copolymer in a polypropylene glycol medium. The copolymer portion of the composition has a theoretical hydroxyl equivalent of 288, while the total copolymer solution has a hydroxyl equivalent of 444.

As described in the preceding'par'agraph, 17.5 gramsof the 50 percent copolymer solutionof this example (0.034 hydroxyl equivalent of the copolymer and 0.029 hydroxyl equivalent of the glycol) are combinedwith 14.3 g rains (0.193 anhydride equivalent) of phthalic anhydride, 18.3 grams (0.096 epoxide equivalent) of Epoxide 190 and 0.25 gram of dimethylaminomethyl phenol. The mixture is poured into the mold prepared from glass plates and is heated in a circulating oven for thirty minutes at C. followed by a two hour post cure at C. The cured casting has these physical properties:

Following the procedure of Example 7, 300 grams of polyethylene glycol are heated to 120 C. The monomercatalyst solution, prepared by mixing together the methyl methacrylate, the acrylamide, the Z-hydroxypropyl methacrylate, and 6.0 grams of benzoyl peroxide, is then added to the heated glycol solvent through the dropping funnel over a period of 80 minutes at a temperature of 120 C. After all of the monomer-catalyst solution is added, the flask contents are heated at 120 C. for an additional two hours. The charge is cooled to 60 C., 1.5 grams of benzoyl peroxide are added, and the reaction mixture is heated at 120 C. for four more hours. The resulting composition is a 50 percent solution of 60/20/20 methyl methacrylate/racrylamide/2 hydroxypropyl methacrylate copolymer dissolved in polyethylene glycol. The copolymer component of the solution has a theoretical hydroxyl equivalent of 720; the solvent portion of the copolymer solution has a theoretical hydroxyl equivalent of 150; while the total copolymer solution has a theoretical hydroxyl equivalent of 435.

What is claimed is:

1. A process for the preparation of a cross-linked hydroxy copolymer which comprises forming a solution of an uncross-linked hydroxy copolymer devoid of solvent hoiling below 150 C. by polymerizing, at a temperature of from 60 C. to about 150 C., a solution comprising (A) an unsaturated hydroxy monomer selected from the group consisting of monoethylenically unsaturated alcohols, hydroxyalkyl vinyl sulfides and hydroxyalkyl esters of u,fi-ethylenically unsaturated carlboxylic acids of not over four carbon atoms, the alkyl groups of said sulfides and esters having not more than ten carbon atoms,

(B) a different monoethylenically unsaturated monomer copolymerizable with said (A), and

(C) as the sole polymerization solvent, an alcohol, said (C) (1) being a solvent for and non-reactive with said (A), said (B) and said uncross-linked hydroxy copolymer under the polymerization conditions used,

(2) being present in an amount sufiicient todissolve said (A), said (B) and said uncross-linked hydroxy copolymer,

(3) being saturated or containing unsaturation which is non-reactive under the polymerization conditions used,

(4) having a melting point below the polymerization temperature,

(5) having a boiling point of at least 150 C.,

(6) having a viscosity not exceeding centipoises at the polymerization temperature, and,

(7) being capable of entering the curing reaction when said uncross-linked hydroxy copolymer is cured, adding to said uncross-linked hydroxy copolymer solution a polyfunctional compound reactive with hydroxyl groups and selected from at least one member of the group consisting of a polyepoxide and a mixture of a polyepoxide with a polycarboxylic acid anhydride, in an amount sufficient to provide a cross-linked, thermoset composition, and heat-curing the resulting composition.

2. A process as described in claim 1 wherein said (A) is 2-hydroxyethyl acrylate.

3. A process as described in claim 1 (A) is 2-hydroxyethyl methacrylate.

4. A process as described in claim 1 (A) is Z-hydroxypro-pyl acrylate.

5. A process as described in claim 1 (A) is 2-hydroxypropyl methacrylate.

6. A process as described in claim 1 (C) is a polyhydric alcohol.

7. A process as described in claim 1 wherein said (C) is a polyoxyalkylene glycol having a molecular weight of 300 to 4000.

8. A process as described in claim 7 wherein said polyfunctional compound is a polyepoxide.

9. A process as described in claim 7 wherein said polyfunctional compound is a mixture of a polyepoxide and a polycarboxylic acid anhydride.

10. A process as described in claim 7 wherein said polyfunctional compound is a mixture of a diglycidyl ether of 2,2bis(4-hydroxyphenyl)propane and phthalic anhydride.

11. A process as described in claim 9 wherein said polyepoxide and said polycanboxylic acid anhydride are added in amounts suflicient to provide a polycarboxylic acid anhydride:polyepoxidezuncross-linked hydroxy c0- polymer-alcohol system having the ratio of 1-2 equivalents of said polycarboxylic acid anhydride to 2 equivalents of said polyepoxide to 0.2-0.8 equivalent of said uncrosslinked hydroxy copolymer-alcohol mixture.

wherein said wherein said wherein said wherein said References Cited by the Examiner UNITED STATES PATENTS 2,636,015 4/1953 Schmutzler 26033.4 2,681,897 6/1954 Frazier et al. 260784 2,729,623 1/ 1956 Gregg 260837 2,826,562 3/1958 Shokal 260837 2,961,423 11/1960 Chapin 260837 3,037,958 6/1962 Ingram et a1. 26033.6 3,052,659 9/1962 Woodrufl 26033.4 3,070,564 12/1962 Roeser 26033.6

MURRAY TILLMAN, Primary Examiner.

DANIEL ARNOLD, WILLIAM H. SHORT, MORRIS LIEBMAN, Examiners.

B. S. LEON, A. O. DENT, E. B. WOODRUFF,

Assistant Examiners. 

1. A PROCESS FOR THE PREPARATION OF A CROSS-LINKED HYDROXY COPOLYMER WHICH COMPRISES FORMING A SOLUTION OF AN UNCROSS-LINKED HYDROXY COPOLYMER DEVOID OF SOLVENT BOILING BELOW 150*C. BY POLYMERIZING, AT A TEMPERATURE OF FROM 60*C. TO ABOUT 150*C., A SOLUTION COMPRISING (A) AN UNSATURATED HYDROXY MONOMER SELECTED FROM THE GROUP CONSISTING OF MONOETHYLENICALLY UNSATURATED ALCOHOLS,HYDROXYALKYL VINYL SULFIDES AND HYDROXYALKYL ESTERS OF A,B-ETHYLENICALLY UNSATURATED CARBOXYLIC ACIDS OF NOT OVER FOUR CARBON ATOMS, THE ALKYL GROUPS OF SAID SULFIDES AND ESTERS HAVING NOT MORE THAN TEN CARBON ATOMS, (B) A DIFFERENT MONOETHYLENICALLY UNSATURATED MONOMER COPOLYMERIZABLE WITH SAID (A), AND (C) AS THE SOLE POLYMERIZATION SOLVENT, AN ALCOHOL, SAID (C) (1) BEING A SOLVENT FOR AND NON-REACTIVE WITH SAID (A), SAID (B) AND SAID UNCROSS-LINKED HYDROXY COPOLYMER UNDER THE POLYMERIZATION CONDITIONS USED, (2) BEING PRESENT IN AN AMOUNT SUFFICIENT TO DISSOLVE SAID (A), SAID (B) AND SAID UNCORSS-LINKED HYDROXY COPOLYMER, (3) BEING SATURATED OR CONTAINING UNSATURATION WHICH IS NON-REACTIVE UNDER THE POLYMERIZATION CONDITIONS USED, (4) HAVING A MELTING POINT BELOW THE POLYMERIZATION TEMPERATURE, (5) HAVING A BOILING POINT OF AT LEAST 150*C., (6) HAVING A VISCOSITY NOT EXCEEDING 130 CENTIPOISES AT THE POLYMERIZATION TEMPERATURE, AND (7) BEING CAPABLE OF ENTERING THE CURING REACTION WHEN SAID UNCROSS-LINED HYDROXYL COPOLYMER IS CURED, ADDING TO SAID UNCROSS-LINKED HYDROXY COPOLYMER SOLUTION A POLYFUNCTIONAL COMPOUND REACTIVE WITH HYDROXYL GROUPS AND SELECTED FROM AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF A POLYEPOXIDE AND A MIXTURE OF A POLYEPOXIDE WITH A POLYCARBOXYLIC ACID ANHYDRIDE, IN AN AMOUNT SUFFICIENT TO PROVIDE, A CROSS-LINKED, THERMOSET COMPOSITION, AND HEAT-CURING THE RESULTING COMPOSITION. 